1. Field of the Invention
The present invention relates to a water absorptive fabric, and a process suitable for producing such a water absorptive fabric.
2. Discussion of the Prior Art
A water absorptive fabric is used for various purposes. A water cut-off layer used in a communication cable is one example of application of the water absorptive fabric. Generally, the water absorptive fabric is prepared by impregnating a non-woven fabric substrate with a water absorptive composition containing sodium acrylate monomer and a suitable cross-linking agent, heating the impregnated substrate to thereby polymerize the monomer of the water absorptive composition, and finally drying the substrate. The water absorptive fabric thus prepared has a relatively large water absorbing capacity. Where the fabric is used as the water cut-off layer provided in an optical fiber cable, for example, it is desired that the water absorptive fabric has a sufficiently high coefficient of water absorption or a sufficiently high ratio of hygroscopic swelling or expansion. To this end, the amount of sodium acrylate used for impregnating the substrate is usually increased. However, the increase of the sodium acrylate tends to cause increased hardness of the produced non-woven fabric due to cross-linking of sodium polyacrylate, resulting in reduced flexibility of the fabric, and increased difficulty in bending, folding or otherwise handling the fabric to meet a specific application requirement.
For solving the above drawback, it is proposed to use an elastomer such as ethylene-propylene rubber, together with sodium acrylate. This solution suffers from another drawback, namely, reduction in the degree or ratio of hygroscopic swelling or expansion of the water absorptive fabric, whereby the obtained fabric cannot be suitably used for such applications that require the fabric to be able to swell in a sufficient degree absorbing a large amount of aqueous components.